Newick Tree — Topology Only, No Branch Lengths (.nwk)
The identical tree topology with every branch length and support value stripped, which is what a Newick writer produces when the source tree has no lengths. Comparing the two proves a parser distinguishes 'length zero' from 'no length recorded'.
(((TAXON_A,TAXON_B),(TAXON_C,TAXON_D)),TAXON_E,TAXON_F);
Specifications
- Leaves
- 6
- Internal Nodes
- 3
- Has Branch Lengths
- false
- Has Support Values
- false
- Same Topology As
- the branch-length twin
- Characters
- 54
Testing contract
Expected to pass- Scenario
- Parse both Newick twins and compare their topologies and their branch-length attributes.
- Expected result
- The two trees are topologically identical over the same six leaves, and every branch here reports an absent length rather than a length of zero.
What is a .nwk file?
Newick is a compact parenthetical notation for trees, used across phylogenetics. Nested parentheses describe the topology, commas separate siblings, names label leaves and optionally internal nodes, a colon introduces a branch length, and a semicolon terminates the tree. Internal-node labels are frequently repurposed to carry bootstrap support values, which is why a parser must not assume a label is a taxon name.
How to use this file
Use an example .nwk file to test tree parsers and phylogeny viewers, checking quoted labels containing punctuation, missing branch lengths, unrooted versus rooted forms, and that deeply nested trees do not overflow a recursive reader.
How to use this file for testing
“Newick Tree — Topology Only, No Branch Lengths (.nwk)” is a deterministic Novus Examples fixture for Scientific data, Editor testing, Conversion testing. Citation catalogs (BibTeX, RIS), chemistry structures (MDL Molfile, PDB), and gridded binary data (NetCDF, FITS) — for testing reference managers, molecule viewers, and scientific-data loaders.
Documented properties for this file: NWK · 57 bytes. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.
Scientific fixtures are small, valid, and fully synthetic — no real organism, patient, sample, or observation. Point your parser or loader at the file and check it reads the documented records, variables, or headers; binary formats ship a readable twin or metadata listing for comparison.
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